Fracturing pump assembly

ABSTRACT

An improved fracturing pump is provided. The pump is reconfigurable on site. The pump uses a bull gear/pinion drive arrangement that increases reliability and efficiency. Internal components of the pump may be varied to meet the requirements of a specific operation. The reconfiguration gives the user the ability to increase or decrease the horsepower of the pump. A closed loop oil feed system provides constant and reliable lubrication even under heavy loads. The sealing system is enhanced to reduce leaks and thermal stresses. The pump also has an improved frame and chassis to reduce NVH and enhance reliability.

BACKGROUND OF THE INVENTION 1. Field of the Invention

This invention relates to pumps, and in particular, to an improved fracturing pump assembly.

2. Description of the Prior Art

Drilling and production systems are often employed to access and extract hydrocarbons from subterranean formations. These systems may be located onshore or offshore depending on the location of a desired resource. Further, such systems generally include a wellhead assembly mounted on a well through which the resource is accessed or extracted. These wellhead assemblies may include a wide variety of components, such as various casings, valves, pumps, fluid conduits, and the like, that control drilling or extraction operations.

Drilling and production operations, such as fracking, employ fluids referred to as fracturing or drilling fluids to provide lubrication and cooling of the drill bit, clear away cuttings, and maintain desired hydrostatic pressure during operations. Fracturing can include all types of water-based, oil-based, or synthetic-based drilling fluids. Fracturing pumps can be used to move large quantities of fracturing from surface tanks, down thousands of feet of drill pipe, out of nozzles in the bit, back up the annulus, and back to the tanks. Operations come to a halt if the fracturing pumps fail, and thus, reliability under harsh conditions, using all types of abrasive fluids, is of utmost commercial interest. Also, portability of these pumps is an issue, so having a versatile pump which can meet the needs of virtually any situation would be desirable.

An improved fracturing pump is provided. The pump is reconfigurable on site. The pump uses a bull gear/pinion drive arrangement that increases reliability and efficiency. Internal components of the pump may be varied to meet the requirements of a specific operation. The reconfiguration gives the user the ability to increase or decrease the horsepower of the pump. A closed loop oil feed system provides constant and reliable lubrication even under heavy loads. The sealing system is enhanced to reduce leaks and thermal stresses. The pump also has an improved frame and chassis to reduce NVH and enhance reliability.

SUMMARY OF THE INVENTION

It is a major object of the invention to provide an improved fracturing pump assembly.

It is another object of the invention to provide a fracturing pump assembly with interchangeable parts.

It is another object of the invention to provide a fracturing pump assembly with a variable power output.

It is another object of the invention to provide a fracturing pump assembly with an improved crosshead design.

It is another object of the invention to provide a fracturing pump assembly having a fluid end with a 45 degree valve seat.

It is another object of the invention to provide a fracturing pump assembly having an improved frame which utilizes partition support.

It is another object of the invention to provide a fracturing pump assembly where the pump frame is integrated into the skid chassis.

It is another object of the invention to provide a fracturing pump assembly with a closed loop lubricating system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 generally depicts a wellsite system, in accordance with one or more implementations described herein.

FIG. 2 shows a side cutaway view of a prior art pump.

FIG. 3 shows a perspective view of the fracturing pump assembly of the invention.

FIG. 4 shows a perspective view of a second embodiment of the fracturing pump assembly of the invention.

FIG. 5 is a diagram of the closed loop oil feed system of the invention.

FIG. 6 is a system flowchart depicting operational aspects of the assembly of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Generally speaking, FIG. 1 illustrates a wellsite system in which the inventive fracturing pump can be employed. The wellsite system of FIG. 1 may be onshore or offshore. In the wellsite system of FIG. 1, a borehole 11 may be formed in subsurface formations by rotary drilling using any suitable technique. A drill string 12 may be suspended within the borehole 11 and may have a bottom hole assembly 100 that includes a drill bit 105 at its lower end. A surface system of the wellsite system of FIG. 1 may include a platform and derrick assembly 10 positioned over the borehole 11, the platform and derrick assembly 10 including a rotary table 16, kelly 17, hook 18 and rotary swivel 19. The drill string 12 may be rotated by the rotary table 16, energized by any suitable means, which engages the kelly 17 at the upper end of the drill string 12. The drill string 12 may be suspended from the hook 18, attached to a traveling block (not shown), through the kelly 17 and the rotary swivel 19, which permits rotation of the drill string 12 relative to the hook 18. A top drive system could alternatively be used, which may be a top drive system well known to those of ordinary skill in the art.

In the wellsite system of FIG. 1, the surface system may also include drilling fluid 26 (also referred to as fracturing) stored in a pit/tank 27 at the wellsite. A pump 29 supported on a skid 28 may deliver the drilling fluid 26 to the interior of the drill string 12 via a port in the swivel 19, causing the drilling fluid to flow downwardly through the drill string 12 as indicated by the directional arrow 8. The drilling fluid 26 may exit the drill string 12 via ports in a drill bit 105, and circulate upwardly through the annulus region between the outside of the drill string 12 and the wall of the borehole 11, as indicated by the directional arrows 9. In this manner, the drilling fluid 26 lubricates the drill bit 105 and carries formation cuttings up to the surface, as the drilling fluid 26 is returned to the pit/tank 27 for recirculation. The drilling fluid 26 also serves to maintain hydrostatic pressure and prevent well collapse. The drilling fluid 26 may also be used for telemetry purposes. A bottom hole assembly 100 of the wellsite system of FIG. 1 may include logging-while-drilling (LWD) modules 120 and 120A and/or measuring-while-drilling (MWD) modules 130 and 130A, a roto-steerable system and motor 150, and the drill bit 105.

FIG. 2 shows a cutaway side view of a prior art fracturing pump, illustrating various components of the power assembly, the portion of the pump that converts rotational energy into reciprocating motion. A pump as shown in FIG. 2 could be used as pump 29 of FIG. 1, although many other fracturing pumps, including those with designs described below in accordance with certain embodiments of the present technique, could instead be used as pump 29. Pinion gears 52 along a pinion shaft 48 drive a larger gear referred to as a bull gear 42 (e.g., a helical gear or a herringbone gear), which rotates on a crankshaft 40. Pinion shaft 48 is turned by a motor (not shown). The crankshaft 40 turns to cause rotational motion of hubs 44 disposed on the crankshaft 40, each hub 44 being connected to or integrated with a connecting rod 46. By way of the connecting rods 46, the rotational motion of the crankshaft 40 (and hub 44 connected thereto) is converted into reciprocating motion. The connecting rods 46 couple to a crosshead 54 (a crosshead block and crosshead extension as shown may be referred to collectively as the crosshead 54 herein). The crosshead 54 moves translationally constrained by guide 57. Pony rods 60 connect the crosshead 54 to a piston 58. In the fluid end of the pump, each piston 58 reciprocates to move fracturing in and out of valves in the fluid end of the pump 29.

Referring now to FIGS. 3-4 two embodiments of the pump 100, 200 are shown. It can be appreciated that pump 100 is a triplex pump and pump 200 is a quintuplex pump. The two pumps 100, 200 function in the same manner except as otherwise noted. It can be seen that the pump 100 has a crankshaft 102, which drives connecting rods 104, which ultimately cause reciprocating action of the pistons 106 to create pumping action as in the prior art model. The conventional style crankshaft 102 is mounted on the power end frame with strong bearing housing to support the self aligned, double—row roller bearings on every frame plate to deliver maximum life. In a key aspect of the invention, the crankshaft 102 is connected to connecting rods vis a bull gear pinion drive arrangement. The bull gears & pinion gear are machined to AGMA 10 specification from forged high alloy steel and heat treated for Dura-last service life. The gears featuring a helical gear profile, are mounted securely to the crankshaft with high strength bolts.

By increasing the size of key components such as the crossheads 116, and crankshaft 102 the pump 100 can handle greater loads. A closed loop oil feed system 118 is part of an optimized lubrication system which reduces friction between crosshead 116 and crosshead guides 117. Low operating lube oil temperatures and high mechanical efficiency increase reliability.

A robust sealing system is provided to improve leak and thermal stresses handling during harsh high temperature Frac operation in the field. As previously stated, the interior components of the pump, including the plunger 140, can be interchangeably replaced to increase power output, a key aspect of the invention. Stroke length can be varied between 8 and 11 inches, with corresponding variances in output power. In a preferred embodiment power generation ranges from 1800HP to 2250HP. Also, the pump allows variable high pressure output and high flow rate based on variance of plunger size.

Crosshead 116 is designed to improve friction issues and reduce wear and noise and integrate with two piece crosshead head as alternative design. A closed loop fluid system to increase stroke component life and improve lubrication is described below

The bull gears and pinion shaft are forged and heat treated, made from alloy steel, with the helix gear machined to AGMA grade 10. The teeth surface of the pinion shaft are surface hardened to BHN 360. The bearings are preferably premium SKF or equivalent with a minimum life of 30,000 hours at rated load. Crosshead 116 is made of cast iron and may include an optimized electric lube system. High temperature rubber seals are used throughout to improve sealing and reliability. Adding fluid channels as described and shown in FIG. 5 below allows for better lubrication of components, as well as better lubricant distribution, and reduces thermal stress. Finally, a new sealing design using fluid mechanics applications to eliminate leak and increase sealing life.

Referring now to FIG. 4 a quintuplex variation of the pump 200 is shown. The variation of pump 200 includes a crankshaft 202 and function to operate plungers 204 which effect pumping action. The size of plungers 204 can be varied to allow for variable pumping output as in the prior embodiment 100.

Power end frame plates 206 are designed and built from high strength grade steel alloy yet optimized for light weight.

In a key aspect of the invention, the pump frame and skid are integrated to provide rigidity and reduce deflection of stroke components and increase life cycle and durability.

FIGS. 5 and 6 show the closed loop lubrication system 140. The purpose of the closed loop oil lubrication system is to provide cooling to the stroke components, increase the life of the stroke components such as the crosshead, connector rod bearing and crankshaft bearing.

Efficient lubrication and reduced contamination will increase durability and life of the stroke components. More efficient lubrication circulation and effective contamination reduction will immediately reduce overheating and reduce failure.

The flow diagram shown in FIG. 5 circulates oil or lubricant to stroke components and the crankshaft bearing of the pumps 100, 200. The oil loop lines circulate from the oil tank with action of the feed pump 198. Flow regulation is accomplished with check valves 9, relief valve 7, and filters 5, and 6 to eliminate contamination. A solenoid (not shown) is to improve and regulate steady pressure to the stroke components as shown in the diagram. Oil re-circulated from the pump 100, 200 is cooled by a heat exchanger 201 before being re-circulated via tank or reservoir 4.

It is to be understood that the present invention is not limited to the sole embodiment described above, but encompasses any and all embodiments within the scope of the following claims: 

I claim:
 1. A fracturing pump assembly comprising: a frame having a plurality of bores formed therethrough; and a plurality of crossheads disposed in the plurality of bores, respectively, and adapted to reciprocate therein; a crankshaft for imparting motive power to a plunger, said plunger situated in the fluid handling end of the pump and connected to a piston, whereby rotation of said crankshaft causes reciprocating movement of said plunger which causes fluid to be expelled from the fluid handling end of the pump, and where said crankshaft is coupled to said piston via a bull gear/pinion drive arrangement.
 2. The assembly of claim 1 wherein said plunger may be varied in size for a variable power output. 